Electro-magnetic or solenoid valve devices are widely used for the control of mining equipment. Usually such devices are housed in rectangular components assembled to one another to form valve units or blocks. It is known to construct such devices so that their respective electromagnet displaces a pivotable lever which in turn axially moves a stem of the valve to change the state of the valve i.e. to open or close the valve. It is necessary with such a construction to adapt the stroke of the armature of the electromagnet as accurately as possible to conform to the stroke of the valve stem taking into account the lever ratio. Some controlled adjustment is however necessary and to achieve this hitherto simple screws and lock nuts have been provided on the actuator levers. Openings are then provided in the housings of the valve devices to permit access to the adjustment screws for the adjustment to be effected. Where the housings of several valve devices are combined as a unit or block it is frequently difficult to have ready access to all the individual adjustment mechanisms. Moreover even if ready access is possible fine adjustments have been difficult to effect in practice.
A general object of the invention is to provide an improved adjustment mechanism for a valve device such that fine, sensitive adjustment is feasible and access is permitted for such adjustment even when valve devices are assembled as a block.